Bayer nails promising PhIII results for new PAH contender riociguat

Bayer is on a roll. Just days after nabbing a speedy FDA approval of its cancer drug Stivarga (regorafenib), Bayer says it has nailed positive Phase III data on its new drug for rare cases of pulmonary arterial hypertension, which sets up an NDA that leave Bayer slugging it out with Actelion ($ATLN) and Gilead ($GILD) for market share in 2014.

The pharma company says that riociguat significantly boosted PAH patients' walking distance, adding 36 to 38 meters in a six-minute test after 12 weeks of therapy compared to a placebo for two groups of patients. And Bayer says it can support an argument that riociguat can be used as a first-line therapy for treatment naïve patients as well as those who have been treated using other therapies. The drug is an oral soluble guanylate cyclase stimulator also in other studies for other types of PH.

Thomson Reuters has pegged analysts' average peak sales projection for riociguat at $480 million, according to a report from Reuters.

"The six-minute walk distance test is a well-validated clinical measure in patients with PAH, and therefore, the results of the PATENT-1 trial are encouraging," said Professor Hossein Ardeschir Ghofrani of University Hospital Giessen, the principal investigator. "These data from the PATENT study suggest that riociguat may be a potential treatment option both for patients who have never been treated for PAH as well as for those who have received prior treatment."

The late-stage success at Bayer further complicates and rapidly changing picture of the PAH market. Actelion is on the verge of detailing its own success with macitentan, the second-gen follow-up to Tracleer, which presents some significant safety risks for the small patient population. Gilead's Letairis--approved in 2007--has been eating into Tracleer's market and United Therapeutics has been trying to guard its revenue stream from treprostinil with a new sustained release formulation now up for a possible approval with a PDUFA date of Oct. 27.